Three of the four injured - Sita Kesarkar, 60, Akshay Kesarkar, 18, and Rohini Jagtap, 47 - were admitted to a hospital.

According to Mumbai fire brigade officials, a large portion of the dilapidated building, Aaraam Society, fell on an adjoining slum area and besides the dead and the injured some more people are believed to be trapped under the debris. The building was located in Vakola area of suburban Santacruz.

The Catherine Chawl in the slum with around three dozen hutments took the hit as the 35-year-old building, which was evacuated a few months ago, came crashing down.

The building was slapped with demolition notices in 2007 and 2008 but these were not implemented following court injunctions.

Relief and rescue operations were continuing with 12 fire tenders having rushed to the site with the personnel of the National Disaster Relief Force and police.

Mumbai Mayor Sunil Prabhu, who visited the disaster site, said the BMC wants more powers to demolish such old and dangerous structures.

"We have written several letters to the state government to enact a suitable law on this as we have to raze dilapidated structures to prevent human casualties," Prabhu said.